1. Field of the Invention
The present invention relates to a method of reducing the amount of black in an image, such that a printer can print the image without or with only a little black ink (or toner).
2. Description of the Related Art
Generally, a common printer performs an automatic determination of an image for being printed according to a print command sent from a user end computer, after which it accordingly mixes in black ink (or toner) to achieve a grayscale effect, thereby saving the consumption of color ink (or toner) as well as achieving a better shadow detail effect. However, for certain situations, an image printed with black ink (or toner) is not desired. For example, when a user utilizes an optical pen (also known as an optical index/optical identification (OID) pen, please refer to http://www.giga.com.tw/english/productpen.htm for more details) to read a speech-purpose print code (mostly in the form of very tiny 2D barcodes) on a certain image, the efficiency of the OID pen may be affected if the image itself also contains a lot of black, since the speech-purpose print code is printed completely or primarily in black.
In known prior art solutions, image processing software is utilized to convert the image from an RGB format into a CMYK format and to eliminate or reduce the K value in the CMYK format. However, one RGB value may correspond to multiple CMYK combinations. Therefore, when the converted image is sent to a printer end, the printer system will still process the remaining CMY values and add a K value to obtain a shadow effect. Moreover, the printed image may look unbalanced because the K value (i.e. the shadow) of the original image is eliminated, while the brighter part remains unchanged.
Therefore, there is a need to provide a method of reducing the amount of black so as to completely avoid the conversion mechanism of adding the K value performed by the printer system, such that the user can obtain a printed image without or with only a little black ink (or toner), thereby mitigating and/or obviating the aforementioned problems.
In order to solve the abovementioned problems, the applicant filed the prior Taiwan Patent Application No. 098139978. However, the major procedure of the prior patent application is to increase the number of pixels by four or nine times, which may result in a poor resolution and a more time-consuming calculation. The present invention can further improve the efficiency of the prior patent application.